Radio frequency identification (RFID) tag devices utilize electromagnetic fields to convey data between the RFID tag devices and an RFID reader. The conveyance of data can be bidirectional and can be wirelessly conveyed across typical distances of one to a hundred feet depending on component arrangements of the RFID tag devices. RFID tag devices can be passive, semi-active, or active, referring to how the RFID tag device is powered. A passive RFID tag device is powered by the reader signal. The passive RFID tag device collects energy from the reader signal and uses the collected energy to power the circuitry and transmit data to the reader. Conventional passive RFID tag devices rely of backscattering to transmit data to a reader. Backscattering refers to a reflection of a signal back in the direction from which the signal originated, specifically reflecting RFID reader transmissions back to the RFID reader that emitted these transmissions. A conventional semi-passive RFID tag device includes its own power source, lacks a transmitter, and uses backscattering to transmit data to a reader. An active RFID tag device contains a battery and an on-tag transmitter and does not need to collect energy from the reader nor does it rely on backscattering for data transmissions.
One field where RFID technology is presently used is for transactions. An RFID tag device identifier can be associated with an account, and money transferred from the account to an authorized recipient upon reading information from the RFID tag device in an authorized manner. One popular use of RFID technology for transactions is in vehicular tolls. A vehicle operator purchases a toll tag that includes an RFID tag device, having an identifier in the RFID tag device. The identifier is associated with a toll account for a toll authority. The vehicle operator places the toll tag in a vehicle and upon passing through a toll gateway where the RFID tag device information is read, a toll fee is debited from the account associated with the toll tag.
Large-scale use of RFID tag devices have favored RFID tag devices that are not reliant on batteries as a power source, as exclusion of a battery greatly increases a life span of the devices, reduces production cost significantly, and significantly shrinks a physical footprint of the RFID tag devices. Reliance on backscattering technologies alone, however, significantly limits the range and utility of RFID tag devices.
What is needed is a battery-less RFID tag device that is less reliant on backscattering technologies to transmit data to a remote reader. Ideally, a battery-less RFID tag device would possess advantages of active RFID tags, such as an ability to initiate a communication with a remote reader as opposed to being dependent upon reactive communications only. Ideally, a battery-less RFID tag, would have a sufficient range to replace active RFID tags in usage situations like vehicular toll payment scenarios requiring an RFID transmission range of twenty feet or more, not typically possible or feasible when conventional passive and semi-passive tags are held against a ground plane. Although the above needs have been recognized in the art, no evident solutions exist, which is a deficiency addressed herein by this disclosure.
Skilled artisans will appreciate that elements in the figures are illustrated for simplicity and clarity and have not necessarily been drawn to scale. For example, the dimensions of some of the elements in the figures may be exaggerated relative to other elements to help to improve understanding of embodiments of the present invention.
The apparatus and method components have been represented where appropriate by conventional symbols in the drawings, showing only those specific details that are pertinent to understanding the embodiments of the present invention so as not to obscure the disclosure with details that will be readily apparent to those of ordinary skill in the art having the benefit of the description herein.